Various liquid handling systems are subject to drawing in a gas, such as air, during operation of the system. It then becomes necessary to remove the gas from the resulting fluid so that the liquid component of the fluid can be used.
One example of a liquid handling system of this type is a beverage dispensing system in which a pump pumps a beverage component such as a juice concentrate or a soft drink syrup to a location, such as a fountain head, where it is mixed with carbonated water. During pumping of the beverage component, air may be drawn into the system, and it is necessary to vent the air from the system.
This venting function is accomplished utilizing a venting apparatus. One known venting apparatus includes a housing having both a liquid outlet through which liquid can leave the chamber and a gas vent through which gas can leave the chamber. A float controlled valve controls the opening and closing of the gas vent to thereby control the flow of gas out of the housing through the gas vent. Because the venting apparatus is downstream of the pump, the interior of the housing may be under a substantial pressure, such as 100 psi, and this creates a differential pressure which tends to hold the valve for the gas vent closed. This differential pressure could be reduced by reducing the cross sectional area of the gas vent at the valve element. However, this would correspondingly reduce the ability of the small cross sectional area vent to perform its function of quickly venting gas from the interior of the housing when the valve opens the gas vent. Rapid venting of the chamber is important to make certain that the gas does not flow into the liquid outlet.
The opening force for the gas vent is provided by the weight of the float when the liquid level within the housing drops. Several inherent constraints can make it difficult for the float to provide enough force to assure that the gas vent will open when desired. For example, the float must be light enough to float in the beverage component and therefore cannot be made substantially heavier to increase the opening force on the valve. In addition, the float cannot be made wider and therefore heavier because the float cannot take up the entire interior of the housing. It is also not desired to enlarge the housing. These factors can make it difficult for the float to operate the valve.